LIFE HISTORIES OF FAMILIAR PLANTS 



carpels, five, ten, fifteen or more stamens, five 

 petals, and a calyx of ^ve sepals. The other 

 group arranged the parts of its flowers in threes ; 

 i.e., three or six carpels, three or six stamens, three 

 petals, and three sepals. Concomitantly, other 

 distinctive features were associated with each of 

 these floral arrangements. The quinary division 

 produced net-veined leaves and had two seed- 

 leaves in each seed ; while the leaves of the 

 trinary form were parallel-veined, and its seeds 

 contained only one seed-leaf. Botanists distin- 

 guish these two groups as monocotyledons and 

 dicotyledons — two ugly names which are used to 

 indicate whether one or two seed-leaves 

 (cotyledons) are contained in the seeds respec- 

 tively. 



From these two great groups of plants have 

 descended all the flowering plants with which we 

 are familiar to-day. Few are the species, how- 

 ever, whose flowers now retain their original 

 numbers of fives or threes in each of their whorls. 

 In the lilies, as we have previousl)^ noted, whorls of 

 three are fairly well maintained, although their 

 three carpels have combined to form one central 

 pistil or ovary of three divisions ; but in the 

 orchids and grasses we find striking instances of 

 divergence from the original trinary arrange- 

 ment. 



In the fivefold group of dicotyledons, the 

 original symmetry is generally much more difficult 

 to follow, although buttercups, dog-roses, daisies, 

 etc., all show traces of their quinary arrangement. 



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